Toughened and reinforced the petroleum-based epoxy resin via thermotropic liquid crystal bio-based counterpart

Significant improvements in the fracture resistance of epoxy resins are highly desirable for various applications, but there is a "seesaw" between toughness and other properties. In this study, we incorporated a bio-based thermotropic liquid crystal epoxy precursor (THMT-EP) containing multi-aromatic s-triazine structure derived from vanillin into petroleum-based counterpart tetraglycidyl-4,4 '-methylene dianiline (TGDDM) with 4,4-diaminodiphenyl sulfone (DDS) as a curing agent, and the cured co-blended resin system was able to immobilize the formed liquid crystal domains in a cross-linked network under optimal curing conditions. The blended system with THMT-EP added at 30 wt% exhibited the largest impact strength (31.1 kJ m-2), which was 90.8 % higher than pristine TGDDM/DDS epoxy resin. When THMT-EP was added at 50 wt%, the flexural modulus and strength of the blended system were as high as 4016 MPa and 171.5 MPa, respectively, which were 5.1 % and 48.5 % higher than those of the TGDDM/DDS system, and the resultant was able to pass the highest V-0 level of vertical combustion test. The above results show that it is feasible to improve the performance of petroleum-based epoxy resins with bio-based thermotropic liquid crystal counterpart.